Pole piece coating generally refers to a process in which a uniformly stirred slurry is evenly coated on the current collector, and the organic solvent in the slurry is dried. The effect of coating has an important impact on battery capacity, internal resistance, cycle life and safety. The reasons for wrinkling during the coating process are as follows:

1. First of all, the installation accuracy of the coating machine must be guaranteed.The coating machine is the key process equipment for the processing of power lithium-ion battery pole pieces. If the overall installation accuracy of the coating machine is low, the installation center of each component deviates from the design center line of the whole machine, or has an angle with the design center.The foil tape will wrinkle badly and the mounting center will have to be adjusted.

2. The excessive parallelism between the rollers will cause the foil belt to wrinkle. It is necessary to carefully check whether the vertical projection plane is not parallel or the horizontal plane is not parallel, and then adjust it.

3. The roughness of the roller surface is too poor, the roller surface is not smooth enough, and there are obvious processing textures, which will also cause the foil belt to wrinkle.

4. The back roller and each passing roller are stuck with foreign objects or use too much water. It needs to be checked frequently, found and cleaned in time, and pay attention not to damage the roller surface.

5. The joint of the foil tape is not good, and the pole piece is wrinkled when the tension on both sides of the foil tape is unbalanced. First adjust the tension adjusting roller under the coating head, and adjust the adjusting roller to the original state after the foil tape is gradually stabilized.

6. When the gap between the two ends of the back roller and the coating roller is not consistent when they are in close contact, the pole pieces are wrinkled. Regardless of whether to coat the first or second side, adjust the gap. Some experts suggest that the gap should be properly enlarged, and then slowly narrowed, while observing the dial indicator scale when the coating roller just touches the foil tape.

7. If the deviation correction system is abnormal, the pole piece will be wrinkled. Check whether the deviation correction system at the front and rear three places is in an automatic state. If the length of both sides of the foil strip is inconsistent, that is, when the sickle is bent too much, the pole piece will be wrinkled, which exceeds the deviation correction ability, so the foil has to be replaced.

8. When the pole piece tension is too large, the pole piece is wrinkled. Check whether the tension setting value is reasonable. Then check whether the rotation of the drive rollers and the rewinding and unwinding rollers is flexible, and deal with the inflexible rollers in time.

9. The pole piece is wrinkled when the back roller's opening stroke is inconsistent. It needs to be checked, confirmed and adjusted by the mechanic. After the back roller and the coating roller are pulled apart, the two sides of the gap are 1mm (see the dial indicator) to start the trial coating. When the trailing is qualified, lock the nut.

10. The surface of the rubber roller of the back roller will undergo periodic elastic deformation during the reuse process, and wrinkling will also occur when a certain degree of deformation remains.

11. The parallel state of each roller is damaged due to the loosening of the roller fastening screws, and wrinkling will occur at this time. In this case, just adjust and tighten it in time.